The phrase "the be-all and end-all" means the most important part of something, the essential element, or the ultimate aim or justification. It implies that something is considered to be of utmost importance or the reason for something else
The phrase originated from William Shakespeare's play Macbeth. In the play, Macbeth uses the phrase when considering the "blow" that will result in the death of King Duncan.
Specifically, Macbeth says, "But this blow might be the be all and the end all," indicating that this action could be both the beginning of his reign and the end of his current situation.
More from BBC:
Shakespeare was a genius with words. It is estimated that he had a vocabulary of 17,000 words (four times that of the average educated person of the time). Of these it has been calculated that he brought over 1,700 new words to the English language as well as inventing many of the phrases and sayings which we still use today.
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Wow, 1700 new words! My hat off to The Bard!!
Guess “the be-all and end-all” could be constant but not a fixed thing in one’s life.
When we were in elementary school, peer pressure could be the be-all and end-all, till we realized it wasn’t; When we first fell in with someone, love could be the be-all and end-all, till we found out it wasn’t; When we started our first job, work could be the be-all and end-all, till we knew it wasn’t; When we have our own children, they were the be-all and end all, till they grew up and left the nest.
So there seems to be no “the be-all and end-all”thingy after all, unless you are one of the great ones like the Bard, or maybe death will truly be the be-all and end-all?? 
Have a great Friday.
Pic of the day: Inside of Nidaros Cathedral in Trondheim where all Norwegian kings have their coronations (note Oslo is the political centre of Norway, while Trondheim, the 3rd largest city of Norway, is the religious centre).
